Nucleoside phosphotransferase of chick embryo

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Abstract
This paper describes a purification procedure and some properties of a nonspecific nucleoside phosphotransferase of chick embryo, an activity which catalyzes the transfer of the phosphate ester from a deoxyribonucleotide or a pyrimidine ribonucleotide to a deoxyribonucleoside acceptor. The enzyme is very unstable to heat, dilution and dialysis and it is almost entirely inactivated by DEAE-cellulose chromatography or gel filtration. A marked enhancement in its stability is caused by numerous nucleotides. In these experiments at least 920-fold purification was obtained by using dTTP (50μm) as nucleotide protector. The enzyme, purified in presence of dTTP, has a molecular weight about 270 000, an isoelectric point of 6.27, a pH optimum of 8.8 and is stable at 37 °C at least for 10 min. In absence of nucleotide protector, nucleoside phosphotransferase is converted at 37 °C or by gel filtration in a very small active form with a lower molecular weight (about 30 000) and a pH optimum of 7.6.

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